# Compose Farm

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<img src="http://files.nijho.lt/compose-farm.png" align="right" style="width: 300px;" />

A minimal CLI tool to run Docker Compose commands across multiple hosts via SSH.

> [!NOTE]
> Run `docker compose` commands across multiple hosts via SSH. One YAML maps services to hosts. Change the mapping, run `up`, and it auto-migrates. No Kubernetes, no Swarm, no magic.

<!-- START doctoc generated TOC please keep comment here to allow auto update -->
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Why Compose Farm?](#why-compose-farm)
- [How It Works](#how-it-works)
- [Requirements](#requirements)
- [Limitations & Best Practices](#limitations--best-practices)
  - [What breaks when you move a service](#what-breaks-when-you-move-a-service)
  - [Best practices](#best-practices)
  - [What Compose Farm doesn't do](#what-compose-farm-doesnt-do)
- [Installation](#installation)
- [Configuration](#configuration)
  - [Multi-Host Services](#multi-host-services)
- [Usage](#usage)
  - [Auto-Migration](#auto-migration)
- [Traefik Multihost Ingress (File Provider)](#traefik-multihost-ingress-file-provider)
- [Comparison with Alternatives](#comparison-with-alternatives)
- [License](#license)

<!-- END doctoc generated TOC please keep comment here to allow auto update -->

## Why Compose Farm?

I used to run 100+ Docker Compose stacks on a single machine that kept running out of memory. I needed a way to distribute services across multiple machines without the complexity of:

- **Kubernetes**: Overkill for my use case. I don't need pods, services, ingress controllers, or YAML manifests 10x the size of my compose files.
- **Docker Swarm**: Effectively in maintenance mode—no longer being invested in by Docker.

Both require changes to your compose files. **Compose Farm requires zero changes**—your existing `docker-compose.yml` files work as-is.

I also wanted a declarative setup—one config file that defines where everything runs. Change the config, run `up`, and services migrate automatically. See [Comparison with Alternatives](#comparison-with-alternatives) for how this compares to other approaches.

<p align="center">
<a href="https://xkcd.com/927/">
<img src="https://imgs.xkcd.com/comics/standards.png" alt="xkcd: Standards" width="400" />
</a>
</p>

Before you say it—no, this is not a new standard. I changed nothing about my existing setup. When I added more hosts, I just mounted my drives at the same paths, and everything worked. You can do all of this manually today—SSH into a host and run `docker compose up`.

Compose Farm just automates what you'd do by hand:
- Runs `docker compose` commands over SSH
- Tracks which service runs on which host
- Auto-migrates services when you change the host assignment
- Generates Traefik file-provider config for cross-host routing

**It's a convenience wrapper, not a new paradigm.**

## How It Works

1. You run `cf up plex`
2. Compose Farm looks up which host runs `plex` (e.g., `server-1`)
3. It SSHs to `server-1` (or runs locally if `localhost`)
4. It executes `docker compose -f /opt/compose/plex/docker-compose.yml up -d`
5. Output is streamed back with `[plex]` prefix

That's it. No orchestration, no service discovery, no magic.

## Requirements

- Python 3.11+ (we recommend [uv](https://docs.astral.sh/uv/) for installation)
- SSH key-based authentication to your hosts (uses ssh-agent)
- Docker and Docker Compose installed on all target hosts
- **Shared storage**: All compose files must be accessible at the same path on all hosts
- **Docker networks**: External networks must exist on all hosts (use `cf init-network` to create)

Compose Farm assumes your compose files are accessible at the same path on all hosts. This is typically achieved via:

- **NFS mount** (e.g., `/opt/compose` mounted from a NAS)
- **Synced folders** (e.g., Syncthing, rsync)
- **Shared filesystem** (e.g., GlusterFS, Ceph)

```
# Example: NFS mount on all Docker hosts
nas:/volume1/compose  →  /opt/compose (on server-1)
nas:/volume1/compose  →  /opt/compose (on server-2)
nas:/volume1/compose  →  /opt/compose (on server-3)
```

Compose Farm simply runs `docker compose -f /opt/compose/{service}/docker-compose.yml` on the appropriate host—it doesn't copy or sync files.

## Limitations & Best Practices

Compose Farm moves containers between hosts but **does not provide cross-host networking**. Docker's internal DNS and networks don't span hosts.

### What breaks when you move a service

- **Docker DNS** - `http://redis:6379` won't resolve from another host
- **Docker networks** - Containers can't reach each other via network names
- **Environment variables** - `DATABASE_URL=postgres://db:5432` stops working

### Best practices

1. **Keep dependent services together** - If an app needs a database, redis, or worker, keep them in the same compose file on the same host

2. **Only migrate standalone services** - Services that don't talk to other containers (or only talk to external APIs) are safe to move

3. **Expose ports for cross-host communication** - If services must communicate across hosts, publish ports and use IP addresses instead of container names:
   ```yaml
   # Instead of: DATABASE_URL=postgres://db:5432
   # Use:        DATABASE_URL=postgres://192.168.1.66:5432
   ```
   This includes Traefik routing—containers need published ports for the file-provider to reach them

### What Compose Farm doesn't do

- No overlay networking (use Docker Swarm or Kubernetes for that)
- No service discovery across hosts
- No automatic dependency tracking between compose files

If you need containers on different hosts to communicate seamlessly, you need Docker Swarm, Kubernetes, or a service mesh—which adds the complexity Compose Farm is designed to avoid.

## Installation

```bash
uv tool install compose-farm
# or
pip install compose-farm
```

<details><summary>🐳 Docker</summary>

```bash
docker run --rm \
  -v $SSH_AUTH_SOCK:/ssh-agent -e SSH_AUTH_SOCK=/ssh-agent \
  -v ./compose-farm.yaml:/root/.config/compose-farm/compose-farm.yaml:ro \
  ghcr.io/basnijholt/compose-farm up --all
```

Or create an alias:
```bash
alias cf='docker run --rm -v $SSH_AUTH_SOCK:/ssh-agent -e SSH_AUTH_SOCK=/ssh-agent -v ./compose-farm.yaml:/root/.config/compose-farm/compose-farm.yaml:ro ghcr.io/basnijholt/compose-farm'
```

</details>

## Configuration

Create `~/.config/compose-farm/compose-farm.yaml` (or `./compose-farm.yaml` in your working directory):

```yaml
compose_dir: /opt/compose  # Must be the same path on all hosts

hosts:
  server-1:
    address: 192.168.1.10
    user: docker
  server-2:
    address: 192.168.1.11
    # user defaults to current user
  local: localhost  # Run locally without SSH

services:
  plex: server-1
  jellyfin: server-2
  sonarr: server-1
  radarr: local  # Runs on the machine where you invoke compose-farm

  # Multi-host services (run on multiple/all hosts)
  autokuma: all              # Runs on ALL configured hosts
  dozzle: [server-1, server-2]  # Explicit list of hosts
```

Compose files are expected at `{compose_dir}/{service}/compose.yaml` (also supports `compose.yml`, `docker-compose.yml`, `docker-compose.yaml`).

### Multi-Host Services

Some services need to run on every host. This is typically required for tools that access **host-local resources** like the Docker socket (`/var/run/docker.sock`), which cannot be accessed remotely without security risks.

Common use cases:
- **AutoKuma** - auto-creates Uptime Kuma monitors from container labels (needs local Docker socket)
- **Dozzle** - real-time log viewer (needs local Docker socket)
- **Promtail/Alloy** - log shipping agents (needs local Docker socket and log files)
- **node-exporter** - Prometheus host metrics (needs access to host /proc, /sys)

This is the same pattern as Docker Swarm's `deploy.mode: global`.

Use the `all` keyword or an explicit list:

```yaml
services:
  # Run on all configured hosts
  autokuma: all
  dozzle: all

  # Run on specific hosts
  node-exporter: [server-1, server-2, server-3]
```

When you run `cf up autokuma`, it starts the service on all hosts in parallel. Multi-host services:
- Are excluded from migration logic (they always run everywhere)
- Show output with `[service@host]` prefix for each host
- Track all running hosts in state

## Usage

The CLI is available as both `compose-farm` and the shorter `cf` alias.

| Command | Description |
|---------|-------------|
| `cf up <svc>` | Start service (auto-migrates if host changed) |
| `cf down <svc>` | Stop service |
| `cf restart <svc>` | down + up |
| `cf update <svc>` | pull + down + up |
| `cf pull <svc>` | Pull latest images |
| `cf logs -f <svc>` | Follow logs |
| `cf ps` | Show status of all services |
| `cf sync` | Discover running services + capture image digests |
| `cf check` | Validate config, mounts, networks |
| `cf init-network` | Create Docker network on hosts |
| `cf traefik-file` | Generate Traefik file-provider config |

All commands support `--all` to operate on all services.

```bash
# Start services (auto-migrates if host changed in config)
cf up plex jellyfin
cf up --all
cf up --migrate        # only services needing migration (state ≠ config)

# Stop services
cf down plex

# Pull latest images
cf pull --all

# Restart (down + up)
cf restart plex

# Update (pull + down + up) - the end-to-end update command
cf update --all

# Sync state with reality (discovers running services + captures image digests)
cf sync              # updates state.yaml and dockerfarm-log.toml
cf sync --dry-run    # preview without writing

# Validate config, traefik labels, mounts, and networks
cf check                 # full validation (includes SSH checks)
cf check --local         # fast validation (skip SSH)
cf check jellyfin        # check service + show which hosts can run it

# Create Docker network on new hosts (before migrating services)
cf init-network nuc hp   # create mynetwork on specific hosts
cf init-network          # create on all hosts

# View logs
cf logs plex
cf logs -f plex  # follow

# Show status
cf ps
```

### Auto-Migration

When you change a service's host assignment in config and run `up`, Compose Farm automatically:
1. Checks that required mounts and networks exist on the new host (aborts if missing)
2. Runs `down` on the old host
3. Runs `up -d` on the new host
4. Updates state tracking

Use `cf up --migrate` (or `-m`) to automatically find and migrate all services where the current state differs from config—no need to list them manually.

```yaml
# Before: plex runs on server-1
services:
  plex: server-1

# After: change to server-2, then run `cf up plex`
services:
  plex: server-2  # Compose Farm will migrate automatically
```

## Traefik Multihost Ingress (File Provider)

If you run a single Traefik instance on one "front‑door" host and want it to route to
Compose Farm services on other hosts, Compose Farm can generate a Traefik file‑provider
fragment from your existing compose labels.

**How it works**

- Your `docker-compose.yml` remains the source of truth. Put normal `traefik.*` labels on
  the container you want exposed.
- Labels and port specs may use `${VAR}` / `${VAR:-default}`; Compose Farm resolves these
  using the stack's `.env` file and your current environment, just like Docker Compose.
- Publish a host port for that container (via `ports:`). The generator prefers
  host‑published ports so Traefik can reach the service across hosts; if none are found,
  it warns and you'd need L3 reachability to container IPs.
- If a router label doesn't specify `traefik.http.routers.<name>.service` and there's only
  one Traefik service defined on that container, Compose Farm wires the router to it.
- `compose-farm.yaml` stays unchanged: just `hosts` and `services: service → host`.

Example `docker-compose.yml` pattern:

```yaml
services:
  plex:
    ports: ["32400:32400"]
    labels:
      - traefik.enable=true
      - traefik.http.routers.plex.rule=Host(`plex.lab.mydomain.org`)
      - traefik.http.routers.plex.entrypoints=websecure
      - traefik.http.routers.plex.tls.certresolver=letsencrypt
      - traefik.http.services.plex.loadbalancer.server.port=32400
```

**One‑time Traefik setup**

Enable a file provider watching a directory (any path is fine; a common choice is on your
shared/NFS mount):

```yaml
providers:
  file:
    directory: /mnt/data/traefik/dynamic.d
    watch: true
```

**Generate the fragment**

```bash
cf traefik-file --all --output /mnt/data/traefik/dynamic.d/compose-farm.yml
```

Re‑run this after changing Traefik labels, moving a service to another host, or changing
published ports.

**Auto-regeneration**

To automatically regenerate the Traefik config after `up`, `down`, `restart`, or `update`,
add `traefik_file` to your config:

```yaml
compose_dir: /opt/compose
traefik_file: /opt/traefik/dynamic.d/compose-farm.yml  # auto-regenerate on up/down/restart/update
traefik_service: traefik  # skip services on same host (docker provider handles them)

hosts:
  # ...
services:
  traefik: server-1  # Traefik runs here
  plex: server-2     # Services on other hosts get file-provider entries
  # ...
```

The `traefik_service` option specifies which service runs Traefik. Services on the same host
are skipped in the file-provider config since Traefik's docker provider handles them directly.

Now `cf up plex` will update the Traefik config automatically—no separate
`traefik-file` command needed.

**Combining with existing config**

If you already have a `dynamic.yml` with manual routes, middlewares, etc., move it into the
directory and Traefik will merge all files:

```bash
mkdir -p /opt/traefik/dynamic.d
mv /opt/traefik/dynamic.yml /opt/traefik/dynamic.d/manual.yml
cf traefik-file --all -o /opt/traefik/dynamic.d/compose-farm.yml
```

Update your Traefik config to use directory watching instead of a single file:

```yaml
# Before
- --providers.file.filename=/dynamic.yml

# After
- --providers.file.directory=/dynamic.d
- --providers.file.watch=true
```

## Comparison with Alternatives

There are many ways to run containers on multiple hosts. Here is where Compose Farm sits:

| | Docker Contexts | K8s / Swarm | Ansible / Terraform | Portainer / Coolify | Compose Farm |
|---|:---:|:---:|:---:|:---:|:---:|
| No compose rewrites | ✅ | ❌ | ✅ | ✅ | ✅ |
| Version controlled | ✅ | ✅ | ✅ | ❌ | ✅ |
| State tracking | ❌ | ✅ | ✅ | ✅ | ✅ |
| Auto-migration | ❌ | ✅ | ❌ | ❌ | ✅ |
| Interactive CLI | ❌ | ❌ | ❌ | ❌ | ✅ |
| Parallel execution | ❌ | ✅ | ✅ | ✅ | ✅ |
| Agentless | ✅ | ❌ | ✅ | ❌ | ✅ |
| High availability | ❌ | ✅ | ❌ | ❌ | ❌ |

**Docker Contexts** — You can use `docker context create remote ssh://...` and `docker compose --context remote up`. But it's manual: you must remember which host runs which service, there's no global view, no parallel execution, and no auto-migration.

**Kubernetes / Docker Swarm** — Full orchestration that abstracts away the hardware. But they require cluster initialization, separate control planes, and often rewriting compose files. They introduce complexity (consensus, overlay networks) unnecessary for static "pet" servers.

**Ansible / Terraform** — Infrastructure-as-Code tools that can SSH in and deploy containers. But they're push-based configuration management, not interactive CLIs. Great for setting up state, clumsy for day-to-day operations like `cf logs -f` or quickly restarting a service.

**Portainer / Coolify** — Web-based management UIs. But they're UI-first and often require agents on your servers. Compose Farm is CLI-first and agentless.

**Compose Farm is the middle ground:** a robust CLI that productizes the manual SSH pattern. You get the "cluster feel" (unified commands, state tracking) without the "cluster cost" (complexity, agents, control planes).

## License

MIT
